This invention relates to a combustion chamber for an internal combustion engine and more particularly to an improved combustion chamber for a fuel direct injected internal combustion engine.
It has been recognized that the fuel efficiency and exhaust emission control for an internal combustion engine may be improved by employing direct cylinder injection. This method of fuel injection is particularly useful in conjunction with two-cycle crankcase compression engines. However, it has been generally the practice to position the fuel injector in the cylinder head of the engine and dispose so that it will spray into a combustion chamber formed primarily by a recess in the cylinder head of the engine. The spray nozzle is generally directed toward the head of the opposing piston.
With this type of combustion chamber, however, it is the normal practice to employ some squish action. That is, the recess in the cylinder head which forms the major portion of the combustion chamber is surrounded by a restricted area formed between the head of the piston and the unrecessed area of the cylinder head. When the piston approaches top dead center, the charge which is compressed in the squish area is forced into the recessed area.
One disadvantage with the use of squish action with previously proposed types of fuel injection is that it does not permit maximum fuel efficiency, particularly at idle and low speed operation. Under these operations, it is the practice to spray the fuel into the combustion chamber in a somewhat stratified fashion so that a homogeneous mixture need not be filled in the entire combustion chamber. However, if a restricted amount of fuel is sprayed into the combustion chamber under low and mid-range running conditions the squish action can cause the rich fuel air mixture to be driven away from the gap of the spark plug causing misfiring or improper combustion.
It is, therefore, a principal object of this invention to provide an improved combustion chamber for an internal combustion engine having direct cylinder injection and wherein good stratification may be obtained even at low and mid-range speeds with significant squish action.
It is a further object of this invention to provide an improved direct injected internal combustion engine wherein it will be insured that a stoichiometric mixture is present at the gap of the spark plug at the time of firing regardless of whether or not squish action is employed.